1. Technical Field
The present invention relates to a liquid ejecting head, a liquid ejecting apparatus, and a method of controlling the liquid ejecting head, and particularly to, a liquid ejecting head, a liquid ejecting apparatus, and a method of controlling the liquid ejecting head effectively applied when a flow passage opening and closing mechanism and a flow passage internal pressure adjustment mechanism are provided in a liquid flow passage of the liquid ejecting head from a liquid supply source.
2. Related Art
As representative examples of liquid ejecting heads ejecting liquid droplets, ink jet recording heads ejecting ink droplets can be exemplified. As the ink jet recording heads, for example, there have been proposed ink jet recording heads including head bodies which eject ink droplets from nozzle openings and flow passage members to which the head bodies are fixed, to which ink is supplied from ink cartridges storing ink, and which supply the ink from the ink cartridges to the head bodies. In such types of ink jet recording heads, back pressures inside heads (reservoirs or pressure chambers) are generally maintained to be negative pressures in order to manage meniscus positions at positions at which continuous ejection is handled. However, there is a concern of bubbles near the nozzle openings being drawn to the nozzle openings due to the negative pressures at the time of wiping or the like. When the bubbles are drawn to the nozzle openings, nozzle clogging may occur.
Accordingly, it is necessary to release the negative pressures when the time of wiping or the like is necessary. For this reason, there has been proposed a liquid ejecting apparatus in which an eccentric cam is disposed as a pressurization mechanism in a side of a flow passage between a negative pressure generation mechanism (difference pressure valve) and a head and the inside of the head is pressurized by the pressurization mechanism via the eccentric cam at the time of wiping (see JP-A-2011-161827). There is also a liquid ejecting apparatus in which a bypass flow passage for pressurization supply is installed and a pressure is applied directly to the inside of the head by a pressurization pump (see JP-A-2011-161844)
However, in JP-A-2011-161827, the volume of the flow passage is changed by bringing the eccentric cam into contact with a tube. Therefore, when the number of nozzles increases, for example, branches are formed downstream from the flow passage, it is difficult to perform a necessary volume change. On the other hand, when the tube is thickened to obtain a large volume change, a flow rate is lowered as the tube is thickened, and thus an exhaust property may deteriorate.
In JP-A-2011-161844, it is difficult to minutely adjust the amount of liquid to be supplied and many fluids may be unnecessarily wasted.
In a liquid ejecting head including a negative pressure generation mechanism for each kind of liquid and a valve (in other words, the valve corresponds to a flow passage opening and closing mechanism) that opens and closes a flow passage for each kind of liquid, when each component is distributed and disposed for each kind of liquid, the size of the liquid ejecting head may be increased. That is, it is necessary to contrive and rationalize the layout of each component. Accordingly, particularly in the liquid ejecting head including the plurality of negative pressure generation mechanisms or the plurality of flow passage opening and closing mechanisms for respective colors, a problem is to develop a reasonable disposition layout as a whole.
When a flow passage internal pressure adjustment mechanism is individually installed for each color inside a flow passage in order to release a negative pressure at the normal time, the size of a flow passage member may be increased. Accordingly, it is necessary to contrive the layout of each component, to begin with, from the flow passage internal pressure adjustment mechanism.
It may be difficult to release a negative pressure temporarily with wiping or the like and form a meniscus proper to a nozzle opening again after end of a wiping work in some cases.
Such problems similarly occur not only in flow passage members used in liquid ejecting heads such as ink jet recording heads but also in flow passage members used in devices other than the liquid ejecting heads.